Intervention with selution SLR™ Agent Balloon for Endovascular Latent Limus therapy for failing AV Fistulas (ISABELLA) Trial: Protocol for a pilot clinical study and pre-clinical results

BACKGROUND

The aim of this pilot clinical study is to evaluate the safety and efficacy of the Selution Sustained Limus Release (SLR)™ sirolimus-coated balloon (M.A. MedAlliance SA, Nyon, Switzerland) for improving the patency of failing arterio-venous fistulas (AVF) in hemodialysis patients. We also present herein a pre-clinical pharmacokinetic and safety evaluation of Selution™ to justify its first use in hemodialysis patients for endovascular access salvage.

METHODS AND RESULTS

This is an investigator-initiated prospective single-center, non-blinded single-arm trial. Forty patients with clinically significant de novo or recurrent stenoses in a mature AVF circuit will be recruited. All stenotic lesions will be prepared with high pressure non-compliant conventional balloon angioplasty (CBA) prior to deployment of the Sustained-Release Selution™ sirolimus drug-eluting balloon. The primary efficacy endpoint is 6-month target lesion primary patency and the primary safety endpoint is freedom from localized or systemic serious adverse events through 30 days. Secondary endpoints of interest include technical and clinical success rates and circuit access patency at 3 and 6 months. Follow-up will occur for 2 years for those patients whose AVFs remain patent. Pharmacokinetic and histological animal safety studies performed with the Selution™ coating formulation showed prolonged arterial tissue retention of sirolimus with therapeutic levels up to 60 days and non-toxic and rapidly declining blood levels. Histological results in animal models demonstrated safety, freedom from intraluminal thrombus, reduction in restenosis by sirolimus elution compared to CBA, and no evidence of embolic phenomena indicative of adverse particulate effects.

DISCUSSION

Long release sirolimus coated balloons may serve as a promising novel alternative therapy to paclitaxel-based technology for treating conduit stenosis secondary to neointimal hyperplasia. Pre-clinical pharmacokinetic and histological animal data are encouraging and provide suggestion of safety and efficacy in this setting. This single-center trial will provide a first step toward demonstration of efficacy and safety of this device for treatment of stenotic fistulas.

A review of the Turned-down Onto Pericapsular-tissue Hemisectioned Amputated Toe (TOPHAT) flap for wound coverage during ray amputations of the toes

INTRODUCTION

Exposure of the adjacent Metatarsal-Phalangeal Joint (MTPJ) commonly occurs after application of Topical Negative Pressure Wound Therapy (TNPWT) for a ray amputation wound. This is due to mechanical soft tissue erosion or trauma to the adjacent digital artery from direct pressure effect. This results in toe gangrene requiring a ray amputation and ultimately a larger wound bed. We describe the use of the Turned-down Onto Pericapsular-tissue Hemisectioned Amputated Toe (TOPHAT) flap - a filleted toe flap to protect the adjacent MTPJ capsule combined with a novel Negative Pressure Wound Therapy with instillation and dwell-time (NPWTi-d) dressing technique. The flap protects the adjacent joint capsule and reduces the wound burden whilst allowing the wound to benefit from TNPWT, thereby accelerating wound healing.

MATERIAL AND METHODS

A retrospective review was conducted of patients with toe gangrene requiring ray amputation that underwent the TOPHAT flap on in our institution from 2019 and 2020. Complications such as wound dehiscence, hematoma, flap necrosis and secondary infection were recorded. Other outcomes recorded were time taken to final skin grafting and time taken for complete wound epithelialization.

RESULTS

9 patients underwent treatment with the TOPHAT flap. 2 patients had flap necrosis. 7 patients progressed to definitive skin coverage with skin grafting. One patient subsequently had progressive arterial disease despite successful skin grafting and required above knee amputation. The mean time to final skin grafting and complete wound epithelialization was 49.5 days and 107.5 days respectively. All patients were satisfied with the outcomes and were able to return to their pre-morbid function.

CONCLUSIONS

The TOPHAT flap has a consistent vascular supply that provides durable soft tissue coverage. It is a robust and easily reproducible technique to accelerate wound healing after ray amputations even in patients with peripheral vascular disease.